THE METHOD OF MILK PRE-TREATMENT FOR CHEESE AND QUARG PRODUCTION

Abstract: A synergy effect of the combination of a disaggregation of milk fat, casein micelle complexes and a partial disaggregation of soluble protein micelle complexes taking place in the homogeniser at a temperature of 55 - 74 DEG C under the pressure of 4-8 MPa, while gradually adding of defined amount of soluble calcium salt, at least in two doses, to the milk before curdling in various steps of the treatment with the aim to optimise the free-bound calcium ratio bringing about a positive effect on the yielding of proteins at curdling is the principal behind the proposed method of milk pre-treatment in the enzymatic cheese and quarg production.

Description: THE METHOD OF MILK PRE-TREATMENT FOR CHEESE AND QUARG PRODUCTION. Area of technique The invention deals with a method of milk pre-treatment for cheese and quarg production, resulting in an increase of the proteins and fats yield from the milk. The present state According to the process by which casein is precipitated from milk, methods of milk processing for curd, cheese and casein production can be divided into two groups - Casein is precipitated from the milk by acidifying to its izoelectric point of pH 4.5, or by enzymes, for example, by rennet. The milk proteins are composed of c. 80 mass % of casein and 20 mass % of other proteins, which are identified as the whey proteins. Both mentioned methods of the casein precipitation cannot avoid the loss of biologically valuable proteins in wastes. To increase the yield of proteins from the treated milk, one must focus on a better use of the whey proteins. Methods of milk pre-treatment, that have so far been used, can be divided into a few groups. In the first group, there are methods based on ultra-filtration, dia-filtration and dehydration. At these procedures, the milk is concentrated in ultra-filtration equipment (for example CS AO 242 219; AO 255 311), or the method of ultra-filtration and dehydration is employed in combination, and the obtained concentrate is then dia-filtrated ( for example DD P 247 832, P 255 472, P 257 577 or DE P 2,035 534, P 2, 064 974, US P 4,449231 ). In the second group, there are methods directed at increasing the protein yield from whey by ultra-filtration, precipitation at an elevated temperature, or by the electric way. By heating at an elevated temperature of above 85 °C, the milk proteins are precipitated from the whey ( CS AO 170 385), or the whey is subjected to heat treatment, while calcium salts are added, and then the whey is subjected to the influence of the ion-exchanger at a normal temperature ( PL P 129 343 ). Another method, which has also been used, adds a concentrate obtained from the whey by ultra-filtration or electrolysis ( SU AO 1 220 608 ) to enrich the milk prior to processing. Another group is represented by methods that utilise the homogenisation of milk at high pressures over 12 MPa which is carried out before cheesemaking. During the homogenisation process casein micelles are partially crumbled which results in the release of carboxyl groups of amino acids that bind free calcium bringing about a higher curdleability of milk ( PL P 93 876 ). The patent ( DD P 257 577 ) is based on a similar principle according to which milk is flowing turbulently through a heater at temperature of 85 - 95 °C under the pressure of 100 - 200 kPa. The simplest and most efficient way of milk pre-treatment is a group of procedures based on the fact that when milk is curdling, ionizable calcium is bound to casein, in which kappa-casein is hydrolysed by proteolytic enzymes. In raw milk, the content of ionizable calcium is sufficient, however, the balance of mineral salts is broken by pasteurisation of the milk. The content of calcium may decrease due to the physiological condition of cows. Therefore, to increase the yield of proteins, the content of calcium in the milk is modified by the addition of calcium salts, what results in a higher curdleability of the milk ( for example CS AO 178 691, PL P 86 491, P 88 360, P 118 079 ). At these known methods of milk pre-treatment by calcium salts, the salts are added before skimming and pasteurisation (CS AO 192 981) and then the milk is heated up to a temperature of 80-90 °C, or they are added before pasteurisation, and consequently after heating the milk the content of insoluble calcium salts decreases due to binding into complex compounds, or due to their replacement by sodium cations (CS AO 184 077, SU AO 1 222 236, PL P 82 699, P 83 265 ). A disadvantage of the above-mentioned procedures of milk pre-treatment for cheese and quarg production is the demanding of a special technological equipment (ultra-filtration, dia-filtration and electrolysis ) or the energy consumption due to necessity of the additional heating of the milk up to higher temperatures above 85 °C, or due to the higher pressure above 200 kPa . At the other procedures, there is necessary to add thermally destabilising compounds, ion-exchangers. Considering the disadvantages, the milk pre-treatment based on the modification of the calcium ratio seems to be the simplest and the most affective, comparing to the means used. A disadvantage of the single treatment of milk by adding a determined amount of calcium salts prior to pasteurisation may be a possible worsening of the consistency of the rennet curd. Therefore, after heating the milk, it is necessary to regulate the concentration of insoluble calcium salts by binding calcium into complex compounds, or by substituting calcium cations for sodium cations. The principle of the invention The mentioned deficiencies can be removed to a large extent by using the method of milk pre-treatment in the production of cheese and quarg according to the invention. The essence of it lies in a physico- chemical disaggregation of milk fat, casein micelle complexes and in the partial disaggregation of soluble protein micelle complexes carried out in the homogeniser at a temperature of 72 - 80 °C under a pressure of 4 - 8 MPa while a defined amount of calcium salts is being added to the milk before curdling. Pasteurisation has been carried out at a temperature of 72 - 90 °C before the disaggregation process. The gradual addition of the defined amount of calcium salts in, at least, two doses during various steps of the treatment has shown to be advantageous. The proposed method can be realised in two basic modifications. In the first modification, the temperature of pasteurisation is held at 85 °C and the temperature of the disaggregation of milk fat, casein micelle complexes, and of the partial disaggregation of soluble protein micelle complexes is held at 55 - 65 °C. In the other modification, an energy - saving pasteurisation is carried out at a temperature of 72 - 74 °C and at the temperature of the disaggregation of milk fat and protein complexes is held at 70 - 74 °C, while the defined amount of soluble calcium salts can be added to the milk before and after the standardisation of microbiological conditions of the milk at a ratio from 1/3 - 1/2 to 2/3 - 1/2 of the defined amount of calcium salts. The gradually addition of calcium salts can be realised in three same doses , with the first dose being added before pasteurisation and the remaining two being added before and after the standardisation of microbiological conditions of the milk before the curdling process. The presented method according the invention utilises a physico- chemical treatment on milk fat, casein micelle complees and soluble protein micelle complexes into the homologizer as a result of this is the disaggregation of the milk fat, the removal of clumps of fat globules from the milk at a considerably lower pressure than by classical homogenisation and at temperature range from 55 - 74 °C. The disaggregation disturbs not only fat clumps but also the complexes of casein micelles and partly complexes of micelles of soluble proteins. This creates favourable conditions for the coagulation of proteins at cheese and quargprocessing. Disaggregation is not necessary to connect with pasteurisation of milk. At cheesemaking of some kind of cheese can take place disaggregation without prior pasteurisation of raw milk. Physico- chemical effects of disaggregation are synergicaly strengthened by simultaneous treatment of another physico- chemical changes which resulting from gradually addition of soluble calcium salts to milk before curdling. The advantage of this solution according the invention consist in minimisation of escape of milk fat into whey, in lowering of the protein content in the whey and thereby in increasing about 5 % , at least, in the total protein yield in comparison with the known comparable methods of cheese- and quargmaking. Lower temperatures at the energy-saving pasteurisation and especially lower pressures necessary at disaggregation of milk fat, casein micelle complexes and soluble protein complexes have a favourable effect on total energy consumption and economic efficiency of this method according to the invention, while the high quality of cheeses and quargs are also maintained. Advantage is also fact, that the method according to the invention does not require further investments or special treatment or equipment. The disaggregation can be done in existent homogenisers. Examples for the realisation of the invention The overall technological process of the milk pre-treatment for enzymatic method of cheese- and quargmaking can be divided into the following groups of operations: pasteurisation of raw milk, disaggregation of the milk fat and protein micelle complexes, the standardisation of microbiological milk conditions and adjustment of milk souring, pre-ripening in the cheesemaking machine, curdling and drying of the rennet curd. In the following examples, the procedure of milk pre-treatment according to the invention is illustrated on three following examples. Example 1 Raw milk intended for the making of a cheese with white mold on surface- Encian type is pasteurised by the high pasteurisation at a temperature 85 °C and disaggregated by means of fully or partly disaggregation in homogeniser: a) The standardised milk of a fat content of 2.75 % is pre-warmed up to temperature of 60 °C and disaggregation of milk fat and disturbing of milk micelle complexes are realised at pressure of 6 Mpa. b) Low-fat cream from the centrifuge is drained to the homogeniser, where before input into the homogeniser the skimmed milk is sucked in from the first regeneration section. Then disaggregation takes place, running at temperature of 65 °C and at pressure 6.5 MPa. A disaggregated portion is then drained back into the first regeneration section of the pasteuriser, where it is connected to the rest of the skimmed milk. After pasteurisation and disaggregation of the milk fat and protein micelle complexes a determined amount of a saturated solution of calcium chloride is added in the milk. Such pre-treated milk after standardisation to a required fat content of 2.75 % and the adjustment of souring activity, is let pre-ripen under usual technological conditions over to next day. Curdling of the milk takes place at an acidity of 8 - 8,6 °SH and at temperature 28 °C. The total time of the milk pre-treatment from curdling to letting out the seed onto the belt conveyer at a higher strengthening takes place among 55 and 70 minutes. Example 2 The one half of total determined amount of the saturated solution of calcium chloride is added in pasteurised milk with fat content in dry matter of 10 % determined for the production of delicate quarg. The milk is then standardised up to a fat content of 0.35 %, pre-heated up to temperature of 65 °C and disaggregated at a pressure of 7 MPa in a homogeniser. Prior to curdling, the other half of the total determined amount of the saturated calcium chloride solution is added and the milk is then processed under usual technological conditions. Example 3 The one third of the total determined amount of the saturated solution of calcium chloride is added into raw milk, which is determined for the production of Edam-type cheese. The milk is then pasteurised by the energy-saving pasteurisation at a temperature 72 °C and then the milk fat and protein micelle complexes are disaggregated in homogeniser. The disaggregation takes place fully or partly: a) when the standardised milk of a fat content of 2.55 % is pre-heated up to a temperature of 72 °C and disaggregated at a pressure of 5.5 MPa. b) when the low-fat cream from the skimmer is drained into the homogeniser prior to the inlet of the homogeniser, the skimmed milk from the first regeneration section is sucked in. Then disaggregation takes place at temperature 72 °C and a pressure 7,5 MPa. The disaggregated portion is drained back into the first regeneration section of the pasteurizer, where it is added into the rest of the skimmed milk. After pasteurisation and disaggregation of the milk, the second one third of the total determined amount of the saturated calcium chloride solution is then added to milk. Such pre-rreated milk is after the standardisation up to a required fat content of 2.7 % and after adjustment of the souring activity, let pre-ripen under usual technological conditions over to a next day. Then the rest-one third of the total determined amount of the saturated calcium chloride solution is added into the milk in the cheesemaking machine and after adjustment of the acidity, the milk is curdled at temperature 30 - 35 °C and dried at temperature 38 - 45 °C for 50 - 70 minutes. Example 4 Non-pasteurised milk for making of emental 's type cheese is standardised up to a fat content of 2.65 - 2.9 %, pre-heated up to temperature 55 - 65 °C and disaggregated at pressure of 6 MPa in the homogeniser. Curdling of milk after adjustment of souring activity is running at temperature 30 - 35 °C and drying is realised at temperature 52 - 55 °C. Utilisation in industry The method according to the invention can be applied besides the examples also for production of non-traditional mainly semi-hard cheeses of various dry substance and various content of fat in the dry-substance and also for production of quarg.

Claims: PATENT CLAIMS 1. The method of milk pre-treatment for the cheese and quarg production characterised in that a physico- chemical disaggregation of milk fat, casein micelle complexes and in the partial disaggregation of soluble protein micelle complexes is carried out into the homogeniser at a temperature of 72 - 80 °C under a pressure of 4 - 8 MPa after pasteurisation has been carried out at a temperature of 72 - 90 °C, while a defined amount of calcium salts is being added to the milk before curdling. 2. The method of milk pre-treatment for the cheese and quarg production as claimed in claim 1, characterised in t h a t the defined amount of calcium salts is gradually adding to the milk, during various steps of the treatment, at least, in two doses. 3. The method of milk pre-treatment for the cheese and quarg production as claimed in claim 1 and 2, characterised in that after the pasteurisation at the temperature of 85 °C the disaggregation of milk fat, casein micelle complexes and the partial disaggregation of soluble protein micelle complexes is being at a temperature of 55 - 65 °C, while the defined amount of soluble calcium salts is being added to the treated milk in two doses, at a ratio from 1/3 - 1/2 to 2/3 - 1/2 of the defined amount, before and after the standardisation of microbiological conditions of the milk. 4. The method of milk pre-treatment for the cheese and quarg production as claimed in claim 1 and 2, characterised in that the after pasteurisation at the temperature of 72 - 74 °C disaggregation of milk fat, casein micelle complexes and the partial disaggregation of soluble protein micelle complexes is being at a temperature of 70 - 74 °C, while the defined amount of soluble calcium salts is being added in three doses, advantageously in the three same doses, before pasteurisation, and before and after the standardisation of microbiological conditions of the milk.

Inventors: PETRANIN GABRIEL, SALUS MILOS, SUBAK JAN, PETRANIN, GABRIEL, SALUS, MILOS, SUBAK, JAN
Applicants: ZEMPMILK A S MICHALOVCE, ZEMPMILK, A.S. MICHALOVCE
Application year: 1994
Main classification: A23C19
IPC codes: A23C19